Process for preparing a detergent tablet

Abstract

The invention provides a process for preparing a detergent tablet having at least one layer and at least one cavity in at least one surface of the tablet holding at least one pre-shaped insert therein, the process including the steps of delivering a cushioning material to the upper surface of the tablet or into the cavity and delivering a pre-shaped insert on top of the cushioning material.

1 . A process for preparing a detergent tablet, having at least one layer and at least one cavity in at least one surface of the tablet holding at least one pre-shaped insert therein, in a tablet press machine comprising a die, a lower punch therein and an upper punch to be lowered towards the lower punch in the die, the process comprising the following steps: 
 a) filling the die with at least one composition to form the at least one layer of the tablet;    b) optionally forming a cavity in the upper surface of the composition with or without simultaneous substantial compression thereof;    c) delivering a cushioning material to the upper surface of the composition or into the cavity formed in step (b), respectively;    d) delivering at least one pre-shaped insert on top of the cushioning material; and    e) compressing the one or more compositions and the pre-shaped insert(s) in a final compression step.    
     
     
         2 . Process according to  claim 1 , wherein step (c) is performed immediately after step (a) without forming any cavity in the upper surface of the composition.  
     
     
         3 . Process according to  claim 1 , wherein, in step (b), a cavity is formed in the upper surface of the composition without any simultaneous substantial compression thereof.  
     
     
         4 . Process according to  claim 1  or  3 , wherein the upper punch comprises at least one portion being relatively movable with respect to the remainder of the upper punch wherein the cavity forming step (b) is performed with the movable portion of the upper punch protruding from the surface thereof and the compression step (e) is performed with the movable portion of the upper punch being retracted to at least the surface thereof.  
     
     
         5 . Process according to any of the preceding claims wherein, in step (a), a multi-layer tablet is formed by sequentially filling compositions for the respective layers into the die and optionally compressing such compositions after each filling step.  
     
     
         6 . Process according to  claim 5  wherein a first composition is filled into the die; the first composition is compressed to form a first layer; and a second composition is filled onto the compressed first layer to form a second layer of the tablet.  
     
     
         7 . Process according to any one of the preceding claims wherein the cushioning material is a meltable material to be dosed in its molten state and being able to harden over the time.  
     
     
         8 . Process according to  claim 7  wherein the cushioning material is a material soluble or dispersible in water or alkaline aqueous solutions.  
     
     
         9 . Process according to  claim 7  or  8  wherein the cushioning material is selected from the group consisting of polymeric material (e.g. polyvinyl pyrrolidone, polyethylene glycol), carboxylic acids e.g. fatty acids), polyols (e.g.  1 , 10  decanediol), sugar derivatives (e.g. sorbitol), and waxes (e.g. paraffin).  
     
     
         10 . Process according to any of the preceding claims, wherein the cushioning material is dosed into a central position on the uppermost layer or into a central position of the cavity, allowing equal spreading of the material throughout the interface between the insert and the cavity during the final compression step.